1. Field of the Invention
The present invention relates to an electric motor including a stator and a rotor arranged at a predetermined spacing from the stator.
2. Description of the Related Art
An electric motor including a rotor and a stator that are arranged to face each other in an axis direction and moving the rotor in the axis direction to change the spacing from the stator is known from the WO2004/088826 Publication.
Now, in an electric motor used in an electric vehicle with wheels operated by an electric motor, a larger amount of magnetic flux is desired because high torque is required at vehicle start and a smaller amount of magnetic flux is desired because a high rotational speed is required during driving at high speed. However, in the disclosure in WO2004/088826 Publication, although the amount of magnetic flux is controlled, accuracy with which to control a gap between the rotor and the stator is not easily increased, which is considered to have effect on the performance of the electric motor.